Panoramic images can either be cylindrical or non-cylindrical. A cylindrical panoramic image has uniform resolution across a span of the panorama while a non-cylindrical panoramic image has varying degrees of resolution across the span of a panorama. Cylindrical panoramas are ideal in conference room situations where parties are seated around a round conference table. Since the parties are equidistant from the panoramic camera, it is suitable that resolution for each camera comprising the panoramic camera be the same.
However, in a situation wherein a conference table is not round (e.g. rectangular), parties are seated at various distances from the panoramic camera. As a result, parties seated farther away from the panoramic camera will appear impractically small in resulting panoramic images unless they are imaged at a higher resolution than parties seated closer to the panoramic camera.
FIG. 1A shows a 360 degree panoramic image 100 of a meeting room. Meeting participants (102, 104, 106) are shown seated around a 10′×5′ conference table 108. The meeting participant 104 seated in between the other meeting participants (102, 106) appears very small compared to the other meeting participants (102, 106) because he is seated farther away from a camera producing the panoramic image 100.
This has at least two negative consequences. First, it is difficult for remote meeting participants (not shown) to see some faces, thus negatively affecting the video conferencing experience. Second, there is a waste of screen space and network bandwidth because a significant number of image pixels are used on the background instead of on the meeting participants.
As technology advances, inexpensive high-resolution panoramic video cameras are becoming more readily available. But due to network bandwidth and user's screen space, only a smaller-sized image can be sent to remote clients. Therefore, how to effectively use the pixels is a critical problem in improving video conferencing experiences.
Techniques—such as non-cylindrical cameras and spatially-varying-uniform (SVU) scaling functions—can be used to solve this problem. FIG. 1B shows a panoramic image 120 similar to the panoramic image 100 shown in FIG. 1A but after head-size normalization. To perform head-size normalization, a camera's position relative to a table on which it rests, an orientation of the camera, and the table size and shape must be known. Current technology requires this information to be entered manually.